Disposable absorbent products, particularly disposable diapers, have come into widespread usage. Such products conventionally have an absorbent or "fluff" layer sandwiched between a liquid impervious sheet (such as polyethylene) and a moisture pervious sheet (such as a non-woven cellulosic material). Methods and machines have been developed to produce these products at relatively good speeds. However, a limitation on speed increase has resided in the formation of the fluff layer. Many machines used for this purpose have employed a fluff forming drum, i.e., a cylindrical device of the general nature seen in U.S. Pat. No. 3,599,293. In such a system shredded cellulosic material is delivered under pressure into the interior of the drum and blown radially outwardly against a conveyor wire traveling about the periphery of the drum. The pressure causes a very dusty operation.
Through the practice of the invention, I have not only avoided the drawbacks of the prior art drum type of fluff former but at the same time have provided a fluff component for an absorbent product which has superior functional characteristics. According to the present invention, two layers of fluff are suction-formed simultaneously on wires advancing along inclined paths relative to their respective fluff housings. Herein, I use the term "wire" in the paper-making sense, having to do with a screen or foraminous type belt such as is found on a paper machine and called a Fourdrinier wire.
After the layers are formed, they are scarffed to a predetermined height and de-bulked. One fluff layer is removed from its wire under suction, and its bottom or "wire side" is brought into contact with a traveling wrap sheet. The wrap sheet and first fluff layer are then moved beneath the second fluff layer which is superposed on the first fluff layer with its top side contacting the top side of the first layer. This results in the wire sides of each layer being disposed outwardly of the combined layers; and the wire side of a fluff layer being denser, the resulting article has better dispersing qualities for body fluids. Further, the fine dust on the wire side is sucked out through the wire. Thus, the sandwich, or dual layer fluff component with the wire side disposed outwardly has the remaining dust trapped inside where it does not affect end use. Speed of operation is enhanced because forming a layer of one-half thickness takes much less time than forming a single layer of the desired thickness.
Persons skilled in the art will appreciate other features and advantages of the invention from the following detailed description, accompanied by the drawing.